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Amplified OTDR systems for multipoint corrosion monitoring.

Nascimento JF, Silva MJ, Coêlho IJ, Cipriano E, Martins-Filho JF - Sensors (Basel) (2012)

Bottom Line: The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment.The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration.Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

View Article: PubMed Central - PubMed

Affiliation: Polytechnic School of Pernambuco, University of Pernambuco (UPE), Recife, PE, Brazil. jehanfonseca@hotmail.com

ABSTRACT
We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

No MeSH data available.


OTDR relative intensity as a function of the Al film corrosion time for the following cases: (a) without gain; (b) 17 dB gain; and (c) 20 dB gain.
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f5-sensors-12-03438: OTDR relative intensity as a function of the Al film corrosion time for the following cases: (a) without gain; (b) 17 dB gain; and (c) 20 dB gain.

Mentions: In Figure 5 we show the temporal evolution of the OTDR trace as the corrosion process takes place on the sensor head number 5, which has 39 nm thick aluminum film deposited on the fiber facet by standard thermal evaporation. We used the Al-etcher 25 H3PO4: 1 HNO3: 5 CH3COOH, which is used in micro device fabrication processes and it has a corrosion rate of Al of 50 nm/min [19]. We used aluminum as the metal for the sensor head and this Al-etcher because of its known etch rate, which is suitable for laboratory experiments. For real applications different metals or other materials should be used in the sensor head to better match to the monitored structure. The sensor head number 5 is dipped in the Al-etcher for short time intervals and the OTDR trace is obtained after each one. As the aluminum is being removed from the fiber facet the reflected light measured in the OTDR decreases. Figure 5 shows the ratio of peak (point B) to valley (point A) of the reflected light shown in Figure 4 as a function of the aluminum corrosion time. Figure 5 shows that up to 30 s of corrosion there is no significant change in the OTDR measured reflected light, since the aluminum is still too thick. Further up from this point the reflection drops to a minimum and then stabilizes at a constant level. The constant level means that the corrosion process on the fiber facet has ended. We obtain the corrosion rate by taking the deposited metal thickness and the time taken to reach the constant level. In Figure 5(a) we show the results for the non-amplified scheme of Figure 3(a), whereas in Figure 5(b,c) we show the results for the amplified scheme shown in Figure 3(b) with 17 dB and 20 dB gain, respectively. In all of them the corrosion of the 39 nm Al film took 47 s, which corresponds to the expected corrosion rate of 50 nm/min. The valley shown in Figure 5(a–c), just before the end of the corrosion process, is a feature that has been preliminarily discussed [5] and will be the subject of future work.


Amplified OTDR systems for multipoint corrosion monitoring.

Nascimento JF, Silva MJ, Coêlho IJ, Cipriano E, Martins-Filho JF - Sensors (Basel) (2012)

OTDR relative intensity as a function of the Al film corrosion time for the following cases: (a) without gain; (b) 17 dB gain; and (c) 20 dB gain.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376602&req=5

f5-sensors-12-03438: OTDR relative intensity as a function of the Al film corrosion time for the following cases: (a) without gain; (b) 17 dB gain; and (c) 20 dB gain.
Mentions: In Figure 5 we show the temporal evolution of the OTDR trace as the corrosion process takes place on the sensor head number 5, which has 39 nm thick aluminum film deposited on the fiber facet by standard thermal evaporation. We used the Al-etcher 25 H3PO4: 1 HNO3: 5 CH3COOH, which is used in micro device fabrication processes and it has a corrosion rate of Al of 50 nm/min [19]. We used aluminum as the metal for the sensor head and this Al-etcher because of its known etch rate, which is suitable for laboratory experiments. For real applications different metals or other materials should be used in the sensor head to better match to the monitored structure. The sensor head number 5 is dipped in the Al-etcher for short time intervals and the OTDR trace is obtained after each one. As the aluminum is being removed from the fiber facet the reflected light measured in the OTDR decreases. Figure 5 shows the ratio of peak (point B) to valley (point A) of the reflected light shown in Figure 4 as a function of the aluminum corrosion time. Figure 5 shows that up to 30 s of corrosion there is no significant change in the OTDR measured reflected light, since the aluminum is still too thick. Further up from this point the reflection drops to a minimum and then stabilizes at a constant level. The constant level means that the corrosion process on the fiber facet has ended. We obtain the corrosion rate by taking the deposited metal thickness and the time taken to reach the constant level. In Figure 5(a) we show the results for the non-amplified scheme of Figure 3(a), whereas in Figure 5(b,c) we show the results for the amplified scheme shown in Figure 3(b) with 17 dB and 20 dB gain, respectively. In all of them the corrosion of the 39 nm Al film took 47 s, which corresponds to the expected corrosion rate of 50 nm/min. The valley shown in Figure 5(a–c), just before the end of the corrosion process, is a feature that has been preliminarily discussed [5] and will be the subject of future work.

Bottom Line: The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment.The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration.Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

View Article: PubMed Central - PubMed

Affiliation: Polytechnic School of Pernambuco, University of Pernambuco (UPE), Recife, PE, Brazil. jehanfonseca@hotmail.com

ABSTRACT
We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

No MeSH data available.